Cordylophora
(euryhaline hydroid)

Pictures

Picture	Title	Caption	Copyright
Title Colony growing on dressenid mussels Caption Colony of Cordylophora growing on dressenid mussels collected from Lake Michigan, USA. July 2003. Copyright Nadine Folino-Rorem	Colony growing on dressenid mussels	Colony of Cordylophora growing on dressenid mussels collected from Lake Michigan, USA. July 2003.	Nadine Folino-Rorem

Identity

Preferred Scientific Name

• Cordylophora Allman, 1844

Preferred Common Name

• euryhaline hydroid

Other Scientific Names

• Cordylophora albicola Kirchenpauer, 1861
• Cordylophora americana Leidy, 1870
• Cordylophora annulata Motz-Kossowska, 1905
• Cordylophora caspia (Pallas, 1771)
• Cordylophora dubia Hargitt, 1924
• Cordylophora fluviatilis Hamilton, 1928
• Cordylophora japonica Itô, 1951
• Cordylophora lacustris Allman, 1844
• Cordylophora lacustris var. otagoensis Fyfe, 1929
• Cordylophora mashikoi Itô, 1952
• Cordylophora pusilla Motz-Kossowska, 1905
• Cordylophora solangiae Redier, 1967
• Cordylophora whiteleggi von Lendenfeld, 1886

International Common Names

• English: European fouling hydroid; freshwater hydroid; Ponto-Caspian hydroid

Local Common Names

• Austria: Keulenpolyp
• Denmark: Brakvands-kollepolyp
• Estonia: jarvetolvik
• Finland: murtovesipolyyppi
• Germany: Keulenpolyp
• Lithuania: Kordylofora
• Netherlands: brakwaterpoliep
• Sweden: Klubbpolyp

Summary of Invasiveness

Cordylophora is referred to as a Ponto-Caspian invasive hydroid presumably originating from the Caspian and/or Black Sea, though this has yet to be confirmed by morphological and molecular analyses. This euryhaline hydroid occurs in fresh and brackish habitats globally with an expanding distribution due to increased ship transport (via hull and ballast water). The spread and establishment seems to be enhanced by the hydroid's physiological ability to acclimate and proliferate in a wide range of salinities (Folino, 2000; bij de Vaate et al., 2002; Janssen et al., 2005). Successful establishment is strengthened via a dormant stage (menont) (Roos, 1979) that has notable regeneration capabilities in varying salinities (Kinne, 1958; N Folino-Rorem, Wheaton College, Illinois, USA, personal communication, 2009). Definitive records for this hydroid as an invasive species are vague though Roch (1924) presents a thorough global summary of documented locations. Cordylophora is not on the IUCN alert list.

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Metazoa
•         Phylum: Cnidaria
•             Class: Hydrozoa
•                 Order: Anthoathecata
•                     Family: Oceanidae
•                         Genus: Cordylophora

Notes on Taxonomy and Nomenclature

The taxonomy of this hydroid at the family and genus level is in a tentative state. Some (Cartwright et al., 2008; Folino-Rorem et al., 2009a) use the provisional family name of Oceaniidae Eschscholtz, 1829 proposed by Schuchert (2004, 2005) whereas others (Calder and Kirkendale, 2005; Jankowski et al., 2008) use the family name Cordylophoridae von Lendenfeld, 1885. Furthermore, other researchers (Bouillon et al., 2006; Stepanjants et al., 2006) use Clavidae McCrady, 1859. Using Oceaniidae or the more historically accurate name of Cordylophoridae at this point in time are recommended until more morphological and molecular data are available to clarify the family status (D Calder, Centre for Biodiversity & Conservation Biology, Royal Ontario Museum, Canada, personal communication, 2009; P Schuchert, Museum d'Histoire Naturelle, Geneva, Switzerland, personal communication, 2009).

Description

Cordylophora is a colonial, athecate euryhaline hydroid occurring in freshwater and brackish habitats globally (Roos, 1979; Folino, 2000). This is one of the few known freshwater Cnidaria and appears be the only freshwater, colonial hydrozoan (Clarke, 1878). Colonies grow on living and non-living hard substrata, with colonies ranging in height from 1-12 cm, though this varies depending on habitat/salinity (Kinne, 1958; Arndt, 1984). Although colony growth is optimal at 15-17 psu at 20°C, this hydroid can tolerate a wide range of salinities (Roch, 1924; Kinne, 1956; Arndt, 1984). Colonies consist of polyps (gastrozooids or hydranths) specialized for feeding or reproduction (gonophores that produce sporosacs) (Allman, 1844; Fraser, 1944). The tentacles on the hydranths use microbasic euryteles and desmonemes nematocysts for capturing prey (Itô, 1951; Stepanjants et al., 2000; Schuchert, 2004). An upright or hydrocaulus can be unbranched or monopodially branched with a terminal hydranth or feeding polyp. Hydranths bear scattered filiform tentacles with a conical hypostome; the number of tentacles typically ranges between 14 and 16 though some can have as many as 27 but this varies relative to salinity (Kinne, 1958; Schuchert, 2004). Colonies sometimes have annulations of the perisarc at the base of an upright or side branch (Calder, 1968; Gosner, 1971; P Schuchert, Museum d'Histoire Naturelle, Geneva, Switzerland, personal communication, 2004). Historically, it is the number, type and arrangement of tentacles on the hydranth that are the primary diagnostic features used in identifying this genus.

Colonies are dioecious possessing either male or female sporosacs (or gonophores) for sexual reproduction. Fertilized eggs develop into free-swimming planula larvae that settle to form a sessile, primary polyp. A medusa stage is lacking (Allman, 1853). Colonies reproduce asexually by budding. Cordylophora survives cold temperatures and periods of unfavourable conditions via small masses of tissues, called menonts, which remain in the perisarc of the hydrocauli and/or uprights. This tissue regenerates when temperatures increase or conditions become more favorable (Kinne, 1971; Roos, 1979; Folino, 2000).

Distribution

Cordylophora occurs on all continents except Antarctica (see pictures). This hydroid is absent from fully marine habitats though colonies demonstrate suboptimal growth in laboratory cultures at higher salinities (30-40 psu) (Kinne, 1958).

In addition to the countries listed in the Distribution Table, Cordylophora is also present in Iceland (Lake Ljosavatn) (R Campbell, University of California, USA, personal communication, 2009) and Thailand (Lam Takong Reservoir, Khorat) (T Wood, Wright State University, Ohio, USA, personal communication, 2009). As well as the records in the table, there are additional reports from: Germany (Ryck River, Greifswald), Ireland (Shannon River, Limerick) and the Netherlands (River Waal, Nijemegen) (N Folino-Rorem, Wheaton College, Illinois, USA, personal communication, 2009);  the USA: California (Napa and Petaluma rivers, San Francisco Bay Area), Illinois (Illinois and Des Plaines rivers, LaSalle Lake, several harbours in Lake Michigan), Massachusetts (Merrimack River, Amesbury), Michigan (Lake Michigan, Muskegon), New Hampshire (Lamprey River, Newmarket; Squamscott River, Exeter; Jackson Landing, Durham), New York (Finger Lakes, Cayuga and Seneca Lakes, Lake Ontario, Rochester), Pennsylvania (Lake Erie, Presque Isle, State Park), Virginia (James River, Jamestown Settlement) (N Folino-Rorem, Wheaton College, Illinois, USA, personal communication, 2009) and West Virginia (Floyd Lake, Harrison County) (R Campbell, University of California, USA, personal communication, 2009); and the United Kingdom (Wraysbury, Middlesex) (R Mant, University of Cambridge, UK and N Folino-Rorem, Wheaton College, Illinois, USA, personal communication, 2009).

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

The global spread and establishment of C.caspia (a Ponto-Caspian invasive species from the Black, Caspian, Azov Seas and surrounding areas) is primarily attributed to increased ship transport through canals and rivers via ship ballast and/or hull fouling (Folino, 2000; bij de Vaate et al., 2002; Pienimäki and Leppäkoski, 2004; Janssen et al., 2005; Streftaris et al., 2005). The hydroid presumably originated in the Black and/or Caspian Seas, spreading west via a northern corridor to the Baltic Sea, a north central corridor toward the North Sea and a southern corridor toward the Mediterranean Sea (bij de Vaate et al., 2002; Ketelaars, 2004). The avenues of rivers and canals to Europe facilitated the establishment in the coastal/estuary areas especially along the North and Baltic Seas. A summary of the spread of C. caspia suggests its presence in the North Sea in 1858 with records in the Rhine River in 1874 (van Riel et al., 2006). It is unclear if the hydroid was present in the Baltic Sea before the North Sea or vice versa. Streftaris et al. (2005) document the occurrence of C. caspia in the Baltic at 1883 and the North Sea in 1884. Additional records document this hydroid in the Baltic Sea in 1870 and being present in 1899 in the Kiel Canal (the canal connecting the North and Baltic Sea) (Gollasch and Rosenthal, 2006). Nevertheless, once established, this hydroid spread to European countries with records of C.caspia in French freshwater systems around 1970 (Devin et al., 2005)

Roch (1924) records the first accounts for Cordylophora in Asia, Africa, and Australia. The earliest record of this hydroid in Central America is from the Panama Canal (Hildenbrand, 1939), obviously transported by ships as a fouler or in ballast water (Cohen, 2006). The first records in North America are for Massachusetts in 1860 (Verrill et al., 1873), while it was later discovered on the west coast of Puget Sound and the San Francisco Bay areas circa 1920 (Cohen et al., 1998; Ruiz et al., 2000; Wonham and Carlton, 2005). Records for Cordylophora (lacustris) in the midwest United States (specifically Kentucky) were published by Garman (1922). Davis (1957) found Cordylophora (lacustris) in the Chargin River in Ohio while Cordylophora (lacustris) was well established in Western Lake Erie by 1972 (Hubschman and Kishler, 1972). Cordylophora spp. supposedly made its way into the Great Lakes via the St Lawrence River System in 1956 (Mills et al., 1993).

Risk of Introduction

The risk of Cordylophora being introduced and/or spreading seems very likely based on its worldwide distribution and changes in water quality due to anthropogenic activity that alters salt concentrations (Hubschman, 1971; Folino, 2000). In addition, the likelihood of new introductions continues with increased shipping (spread via ship ballast and/or hull fouling) (Folino, 2000; bij de Vaate et al., 2002; Pienimäki and Leppäkoski, 2004; Janssen et al., 2005; Streftaris et al., 2005).

Habitat

Because this hydroid is a euryhaline organism, it occurs in both freshwater and brackish habitats (0-32 psu). Whether there are species differences relative to salinity tolerances is yet to be determined (Folino-Rorem et al., 2009a). Colonies are present in tidal areas, rivers, lakes, lagoons and ponds and grow on bivalve shells (e.g., Dreissena, Anodon)(Allman, 1853; Schulze, 1871; Folino-Rorem and Stoeckel, 2006), submerged vegetation (Fyfe, 1929; Roos, 1979; Strayer and Malcom, 2007; El-Shabraway and Fishar, 2009), rocks, wooden pilings, living crab and gastropod shells and floats (Fraser, 1944; Roos, 1979; Gaulin et al., 1986; Barnes, 1994; bij de Vaate et al., 2002; Kautsky, 2008). Estuarine colonies of Cordylophora also occur on eelgrass blades (Chester, 1996), and grow on barnacles (N Folino-Rorem, Wheaton College, Illinois, USA, personal communication, 2009) and oyster Crassostrea virginica shells (Calder, 1971; Carlton, 1979).

Habitat List

Biology and Ecology

Genetics

The karyotype for Cordylophora is n=30 (Stepanjants et al., 2000). The following nucleotide sequences for several populations of Cordylophora spp. are available at GenBank at www.ncbi.nlm.nih.gov/Genbank/index.html: partial sequence; Cartwright et al.: 16S ribosomal RNA gene, partial sequence; mitochondrial; Evans et al. Sch485 28S large subunit ribosomal RNA gene, partial sequence; Folino-Rorem et al: 28S large subunit ribosomal RNA gene. Sequences for Cordylophora mitochondrial 16S rDNA are available at the Hydrozoan Taxonomy site (PEET: Partnerships for Enhancing Expertise in Taxonomy) at: http://www.biology.duke.edu/hydrodb/hydrodb.csv.

Climate

Water Tolerances

Natural enemies

Notes on Natural Enemies

A well-known predator on brackish Cordylophora coloniesis the estuarine nudibranch, Tenellia adspersa. Tenellia is a generalist nudibranch but is often feeds on brackish colonies of Cordylophora causing a noticeable decline in colonies during late summer and early autumn in temperate areas (Harris et al., 1980; Gaulin et al., 1986; Arndt, 1989; Chester, 1996; Blezard, 1999). Furhermore, predation by Tenellia adspersa (a synonym of Embletonia pallida) may graze so heavily on Cordylophora (caspia) colonies causing predator-induced dormancy (Jormalainen et al., 1994; Jewett, 2005). Blezard (1999) demonstrated that fecundity and development of Tenellia were less than optimal at salinities below 12 psu creating a salinity refuge from predation for Cordylophora (lacustris). Another invertebrate predator of Cordylophora hydranths of is the amphipod, Gamarus (Roos, 1979).

The author of this datasheet has knowledge of only one vertebrate predator on Cordylophora caspia, the invasive shimofuri goby (Tridentiger bifasciatus) in San Francisco Estuary, California (Matern and Brown, 2005).

Means of Movement and Dispersal

The majority of citations refer to ship hulls and or ballast water as the primary means of dispersal for Cordylophora (Folino, 2000; bij de Vaate et al., 2002; Pienimäki and Leppäkoski, 2004; Janssen et al., 2005; Streftaris et al., 2005; Cohen, 2006; Fofonoff et al., 2009). Some propose that dispersal could occur via floating plant material drift (Roos, 1979; Koetsier and Bryan, 1989), commercial oysters (Carlton, 1979) and perhaps via birds (Davis, 1957; Green and Figuerola, 2005; Muskó et al., 2008). Reference also has been made to accidental introduction in the Great Lakes by dumping aquaria or via aquatic plants (Mills et al., 1993).

Impact Summary

Economic Impact

Cordylophora acts as a biofouler by colonizing power station cooling systems and fouling industrial water pipes in Europe and North America (Markowski, 1959; Jenner and Janssen-Mommen, 1993; Jenner et al., 1998; Folino-Rorem and Indelicato, 2005; Escot et al., 2007; Venkastesan and Murthy, 2008; Leppäkoski et al., 2009). Often portions of the colonies can break free at the end of the peak growing season and clog filters in the intake tunnels. Increased salts (chlorides) due to evaporation in bodies of water used for cooling at power plants have created more favourable aquatic habitats for Cordylophora in aquatic ecosystems. Furthermore this hydroid is problematic for shipping, boating and fish farming (Leppäkoski et al., 2009).

Environmental Impact

Impacts on Habitats

The potential impact on habitats by Cordylophora is extensive since the organism inhabits freshwater and brackish aquatic habitats of various types (Zaiko et al., 2007). Cordylophora can become very abundant and modify habitats by growing on submerged substrata on soft bottoms changing the community structure of soft bottoms (Olenin and Leppäkoski, 1999). Colonies are capable of creating refuges for and from predators and currents and also assist in the accumulation of particulate organic matter (Leppäkoski, 2004). The filamentous structure of Cordylophora colonies may also serve to enhance the settlement and recruitment of dreissenid mussel larvae (Folino-Rorem and Stoeckel, 2006) and the establishment of macroinvertebrates in zebra mussel colonies by providing more surface area (Moreteau and Khalanski, 1994; Folino-Rorem et al., 2006). In freshwater systems, zebra mussel recruitment is highest in areas of increased vegetation (Stan¢czykowska and Lewandowski, 1993), though this depends on plant architecture (Cheruvelil et al., 2002; Kraufvelin and Salovius, 2004). In addition macrophytes also provide macroinvertebrates with refugia from fish predation (Dykman and Hann, 1996; Warfe and Barmuta, 2004, Harrison et al., 2005). Epiphytes, such as the filamentous alga Cladophora or filamentous epifauna such as the hydroid Cordylophora, may enhance macroinvertebrate colonization of mussel colonies. Folino-Rorem et al. (2006) attributed increased zebra mussel settlement on artificial filamentous substrata (hydroid mimics) to an increase in total surface area rather than a preference for filamentous substrata suggesting that settlement of zebra mussel larvae and other macroinvertebrates on aquatic macrophytes may simply be a function of the increase in substrate surface area afforded by these filamentous organisms. These same filaments facilitated the colonization of chironomids and caddisflies; chironomid and caddisfly densities were significantly greater than on control or plates with no filaments (chironomids: p <0.003; caddisflies: p <0.008) (J Stoeckel & N Folino-Rorem, Wheaton College, Illinois, USA, personal communication, 2009).

Cordylophora caspia has been used an indicator species in its ability to absorb metals such as Cd, Zn and Cu at various salinities (Calmano et al., 1992). Future bioassessment protocols should perhaps consider using this hydroid to detect the presence of toxins in freshwater and brackish habitats.

Risk and Impact Factors

• Invasive in its native range
• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• Highly adaptable to different environments
• Capable of securing and ingesting a wide range of food
• Fast growing
• Has high reproductive potential
• Gregarious
• Reproduces asexually
• Has high genetic variability

• Ecosystem change/ habitat alteration
• Negatively impacts aquaculture/fisheries

• Fouling
• Interaction with other invasive species
• Predation
• Rapid growth

• Highly likely to be transported internationally accidentally
• Difficult to identify/detect as a commodity contaminant
• Difficult to identify/detect in the field
• Difficult/costly to control

Similarities to Other Species/Conditions

Cordylophora colonies occur with other hydroids that are able to tolerate a wide range and/or fluctuations in salinity. In brackish habitats Cordylophora is found with hydroids such as Garveia franciscana (Vervoort, 1964; Arndt, 1984; Ruiz et al., 1999), Gonothyraea loveni and Clavamulticornis (Arndt, 1984).In addition, other co-occurring invasive hydroids found in similar brackish habitats are Maeotias marginata, Blackfordia virginica and Moerisia sp. (Mills and Rees, 2000; Ruiz et al., 2000).

Prevention and Control

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Most attempts to curtail or control the growth of Cordylophora to dateare related to biofouling problems in power plants (Massard and Geimer, 1987; Jenner et al., 1998; Folino-Rorem and Indelicato, 2005; Escot et al., 2007; Venkastesan and Murthy, 2008; Leppäkoski et al., 2009). Methods of eradicating hydroid growth include chlorine and thermal treatments (Rajagopal et al., 2002; Folino-Rorem and Indelicato, 2005). Chlorine and heat combined are advised to curtail growth of Cordylophora (Rajagopal et al., 2002; Folino-Rorem and Indelicato, 2005). Escot et al. (2007) addressed the fouling problems of Cordylophra in a cooling network of the Cartuja'93 technological park in Seville, Spain. They initially attempted to eliminate colonies by manually cleaning pipes. To prevent future colonization, they used a biocide and anti-fouling paint.

Gaps in Knowledge/Research Needs

There are several of areas of necessary research for the invasive hydroid, Cordylophora:

1. One area is clearly needed in the area of taxonomy. It is critical to know how many species are in the genus Cordylophora as we assess the establishment and associated physiological adaptations pertinent for recruitment and establishment.

2. Identifying the most important factors that enhance the survivorship of recruitment in different habitats (especially those that vary in salinity and food availability) is important is assessing the evolutionary potential of Cordylophora species to adapt to new aquatic ecosystems. This would aid in our understanding of the morphological and ecophysiological responses of Cordylophora species to varying environmental regimes.

3. The ecological impact of this hydroid as a predator and as a provider of filamentous substrate in different aquatic ecosystems would add insight about how this invasive hydroid may potentially alter the biological diversity and community dynamics of aquatic habitats.

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14/08/09 Original text by:

Nadine Folino-Rorem, Wheaton College, Biology Department,, 520 Kenilworth Avenue, Wheaton, Illinois 60187, USA

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